Basic Information
Common Name: Bursera excelsa
Scientific Name: Bursera excelsa
Native Habitat: Dry forests, canyons, and rocky slopes of Mexico, primarily found in states like Jalisco, Colima, Guerrero, and Oaxaca.
History / Discovery / Cultivator
Bursera excelsa, a prominent member of the Burseraceae family, holds a significant place in the botanical and cultural history of Mexico. Belonging to a genus renowned for aromatic resins, this species, like many of its relatives, has been utilized by indigenous peoples for centuries. The Burseraceae family, often referred to as the frankincense and myrrh family, is characterized by trees and shrubs containing resinous sap. B. excelsa specifically is noted for producing a type of copal resin, a substance highly valued in pre-Columbian Mesoamerica and continuing its importance today.
Archaeological evidence and historical texts indicate that copal resins from various Bursera species were central to religious ceremonies, incense offerings, medicinal practices, and even as an adhesive and varnish throughout ancient Mexican civilizations, including the Aztecs and Maya. The specific discovery of Bursera excelsa as a distinct botanical entity followed the arrival of European naturalists, who began systematically documenting the flora of the Americas. While the exact date and individual responsible for the formal scientific description of Bursera excelsa might be tied to the broader cataloging efforts of the 18th and 19th centuries, its practical discovery and utilization predate scientific classification by millennia.
Cultivation of Bursera excelsa traditionally centered around the sustainable harvesting of its resin. This often involved making incisions in the bark to collect the sap, which then hardens into copal. This practice continues in some regions. While less commonly cultivated as an ornamental plant globally compared to some other succulents or caudiciforms, Bursera excelsa is appreciated by collectors and botanic gardens for its distinctive trunk, peeling bark, and cultural significance. Its natural adaptation to arid conditions makes it a suitable candidate for xeriscape landscaping in appropriate climates. The understanding and propagation of Bursera excelsa, therefore, combine both ancient traditional knowledge concerning resin extraction and modern horticultural practices aimed at conservation and ornamental cultivation. The plant’s history is intertwined with the landscape and traditions of Mexico, serving as a living link to ancient rituals and natural resource utilization. Its rediscovery, in a sense, is ongoing as its ecological role and horticultural potential continue to be explored beyond its traditional use.
Plant Care Summary
| Category | General Requirement | Notes |
|---|---|---|
| Light | Full sun / Part shade | Prefers full sun for best growth; tolerates some afternoon shade in hotter climates. |
| Water | Infrequent | Drought tolerant. Water deeply when soil is completely dry. Reduce watering significantly in dormancy. |
| Humidity | Low / Moderate | Adapts well to dry conditions. |
| Temp. Range | Warm | Hardy to zone 9/10+. Protect from frost; prefers minimum temps above 40-50°F (5-10°C). |
| Soil Type | Well-draining | Gritty, sandy, or rocky soil. Cactus/succulent mix is ideal. Avoid heavy, waterlogged soils. |
| Fertilizer | Minimal | Light feeding with diluted balanced fertilizer during spring/summer growth. |
| Toxicity | Low toxicity | Generally considered low toxicity. Sap/resin may cause mild skin irritation. |
Botanical Insights
Adaptations
Bursera excelsa is wonderfully adapted to the harsh, arid environments it calls home in Mexico. One of its most notable adaptations is its ability to store water within its trunk and branches, a common trait among succulents and caudiciform plants, although B. excelsa is technically a pachycaul (thick-stemmed) rather than a true caudiform. The trunk often swells at the base, serving as a reservoir. The peeling, papery bark is another distinctive feature; while its exact function is debated, it may help regulate temperature or shed parasites. Perhaps the most famous adaptation of the Bursera genus, including B. excelsa, is the production of aromatic resins. This resin serves multiple purposes: it can seal wounds in the bark, deter herbivores and insects, and potentially reduce water loss through damaged tissues. The plant is also deciduous, shedding its leaves during periods of prolonged drought or cooler temperatures, a crucial water-saving strategy.
Propagation Methods
Propagating Bursera excelsa can be challenging, making large specimens somewhat more prized. The most common method is from seed, which should be sown in a well-draining mix in warm conditions. Germination can be erratic and slow. Propagation from stem cuttings is also possible but requires patience and specific conditions. Cuttings should be taken from mature wood, allowed to callus over for several days or weeks to prevent rot, and then planted in a very well-draining, sterile medium. Providing bottom heat and high humidity (while ensuring the cutting doesn’t rot) can improve success rates, but rooting is often slow and unreliable compared to many other succulents. Air layering is another potential method for thicker branches, but it is less commonly practiced. Due to the difficulty and slow growth from propagation, larger, established plants tend to hold more value.
Toxicology
Generally, Bursera excelsa is considered to have low toxicity for humans and common household pets like cats and dogs. The primary concern relates to the resinous sap. While the resin (copal) has a long history of use in traditional medicine and spiritual practices, direct ingestion of plant parts is not recommended. Contact with the sap or resin could potentially cause mild skin irritation or allergic reactions in sensitive individuals. If ingested, symptoms in pets or humans are unlikely to be severe, possibly limited to mild digestive upset like vomiting or diarrhea due to the resin content. As with any plant not explicitly proven safe, it’s wise to prevent pets from chewing on the plant, particularly young or curious animals. However, it does not contain the highly toxic compounds found in many other common houseplants.
Common Problems
Pests:
- Spider Mites
- Mealybugs
- Scale Insects
Diseases:
- Root Rot
- Stem Rot
Other:
- Leaf Yellowing/Drop (Often due to overwatering or dormancy)
- Lack of Growth (Insufficient light, water, or temperature; also occurs during dormancy)
- Shriveled Stem/Trunk (Severe underwatering or root problems)
Rarity & Value
Rarity:
In its native habitat, Bursera excelsa is not necessarily rare, being found across a significant range in Mexico. However, it is considered less common in cultivation compared to many popular succulents or caudiciforms. This rarity in horticulture stems partly from the challenges of propagation, particularly from cuttings, which makes producing specimens slow and labor-intensive. Furthermore, its niche as a plant best suited for specific arid climates or specialized collections limits its mass-market appeal and availability. Established, mature specimens with impressive caudex or trunk development are particularly uncommon.
Value:
The market value of Bursera excelsa is influenced by several factors. Size and age are primary determinants; older, larger plants with well-developed, interesting trunk structures are significantly more valuable than young seedlings. The overall form and health of the specimen are also crucial. While variegation is not typical for this species, unique growth patterns or particularly aesthetic peeling bark might increase appeal. Its value is often highest among collectors of Burseraceae, caudiforms, and rare succulents. Current demand within these niche collector communities can also impact price, as can the source – ethically sourced or nursery-grown specimens are preferred. Unlike some other plants, the value is less driven by rapid trends and more by the plant’s maturity, form, and inherent botanical interest.
